In the prior art, the conventional procedure has been to use ball milling, stamping, crushing, and grinding operations for breaking up ore-like bodies. This involves, not only a highly objectionable raising of the environmental noise level, but also a great amount of wear and tear on the apparatus and its working parts. Ball milling also tends to produce rounded particles. Accurate and close size selection has been difficult to attain.
Other, more exotic apparatus has employed sudden air pressure changes, with or without a gravity or vacuum induced flow, various fluid utilizing operations, and the directing of the materials against an obstruction with high velocity jets, the exploding or bursting of brittle material by sudden changes of pressure, and so forth.